The micro-service architecture (micro-services or microservices) refers to a computing architectural style in which software applications are deployed as modular services that each run a unique process to perform a discrete business function. The modular services are independent from one another and communicate through a lightweight mechanism, such as Application Program Interfaces (APIs). The micro-service architecture is highly scalable and has revolutionized the way applications are being developed and deployed. For example, the micro-service architecture enables the continuous delivery/deployment/integration of large/complex applications and enables an enterprise/organization to evolve its technology stack.
A software/application container (“container”) is a type of operating system level (OS-level) virtualization technique that allows an application and its dependencies to run as a resource-isolated process. That is, a container is a lightweight, stand-alone, executable package of a piece of software that includes everything needed to run the software, including code, runtime, system tools, system libraries, settings, etc. bundled into one package. Unlike virtual machines (VM), containers have no need for embedded operating systems and calls/requests are made for operating system resources via an API.
Containers and the micro-services architecture are distinct from one another, where a micro-service may run in a container, but a container need not be used for a micro-service. However, containers have lightweight and portability properties which make them well suited for deploying micro-services. For example, container-based micro-services are being widely adopted in the Data Center/Cloud Industry where, rather than building a single large, monolithic application (i.e., a single-tiered software application that is self-contained and independent from other computing applications), the container-based micro-services split the application into a set of smaller, interconnected services.